Contact roll for abrasive belts



W E Wm H. R. HERQHENRHDER fi fi CONTACT ROLL FOR ABRASIVE BELTS Film Amid 2 19% 2 Shams-Shem; E

i0 H. R. HERCHENRBDER CONTACT ROLL FOR ABRASIVE BELTS Fimd Apri'" 2, 1943 2 Sheets-Sheet 2 Afiiarrwas Patented Aug. 2, 1949 CONTACT ROLL FOR ABRASIVE BELTS Henry R. Herchenrider, Mount Lebanon, Pa., as-

slgnor to Minnesota Mining & Manufacturing Company, St. Paul, Minn., a corporation of Delaware Application April 2, 1943, Serial No. 481,537

Claims. 1

This invention relates to grinding and abrading apparatus, especially adapted for use with abrasive belts or like coated abrasives or abrasive sheets. More particularly it concerns an improved form of pressure roll and method for its manufacture.

Heretofore, it has been known to employ pressure rolls or wheels to bring the abrasive into contact with the metal sheets or other material being ground or polished. In structures of this character, it is desirable that the surface of the pressure roll be hard enough to permit of sufiicient pressure against the abrasive-carrying belt to maintain grinding pressure that will permit continued use of the belt after the sharpest structure of the abrasive has been worn down somewhat, until a point at which substantially all of the abrasive has been consumed or used p.

Illustrative of prior suggestions in respect to pressure rolls or contact rolls (for driving abrasive belts and holding the same in contact with the work piece) is my Patent No. 2,162,279, issued June 13, 1939. Said patent discloses a roll which comprises a soft core or body portion of rubber, or like depressible, resilient material, and a facing of hard blocks or shoes which may be of hard rubber, cork or steel, vulcanized or cemented to the soft elastic rubber core. as illustrated in the drawing of said patent. While such construction provides a valuable contribution over art prior thereto, its utility is limited in several respects and I have now found that, by a construction different from that disclosed in said patent, I can produce a pressure roll having a number of advantages.

The pressure roll or contact roll of this invention, in one of its preferred embodiments. as distinguished from having a solid compressible core to the periphery of which harder blocks are cemented or vulcanized, is segmented. Each of the segments of such embodiment is disclosed radially in my pressure roll, the outer ends thereof making up the periphery of the pressure roll or wheel. Each of said segments is an integral unit and has a relatively dense or hard outer portion (to give the wheel or pressure roll a hard or firm surface) and a readily yieldable interior portion. The hard portion of each segment being made integral with the yieldable interior portion, e. g. of a continuous strip of cloth, said segments are not dependent on cementing or vulcanization to resist flying apart, or "blowing up under centrifugal force. Additionally the yieldable inner portion of such segments are not elastically depressible but, rather, are freely compressible in my preferred construction. This pressure roll, during rotation in use, may be likened in principle to a stone tied on a string: Centrifugal force holds the hard outer portions of each'seg- 2 ment out and yet (where the pressure roll is driving an abrasive belt, the back surface of which is in contact with said roll) the segments of the roll will readily depress in accordance with unevenness in the surface of the object being abraded.

The pressure rolls or contact rolls of this invention have special utility in so'-called backstand grinders, as'illustrative hereinafter, e. g. Fig. 1 of the drawing, and have the advantages (1) that they can be operated at increased speeds without fear of their flying apart, (2) areas of the contact surface or periphery thereof can readily be depressed without having to work against an elastic resilient core, and (3) the depressibility of any area of the contact surface is facilitated by the fact that the segments arefree to move sidewise as they depress. These features and their importance, as well as their differences over prior constructions will be further seen from the detailed description given hereinafter.

Accordingly, one of the'objects of this invention is to provide an improved pressure roll of such construction that the surface thereof will be of sufficient hardness to permit of sufficient pressure against the abrasive-carrying belt as to firmly maintain the abrasive grains in contact with the work, and at the same time sufficiently yieldable to permit localized areas of the hardened peripheral surface to freely recede toward the axis of the roll under grinding pressure, except as counteracted by centrifugal force, so that the roll can conform to uneven or irregular areas on the surface being ground or abraded.

Another object of this invention is to provide a pressure roll of such construction that an abrasive sleeve or belt may be easily slipped over the roll when standing and will become firmly held thereon, by friction, when the roll is in motion, by the action of centrifugal force, and then can be easily removed from the roll when not in motion.

' A further object of this invention is to provide a pressure roll of simple construction which can be manufactured economically and conveniently,

Another object is to provide a pressure roll which has superior resistance to blowing up, rupture or explosion at high speeds.

A further object is to provide a contact roll or pressure roll which, when used with abrasive belts or the likejwill result in an improved quality of work, i. e. an improved abrading job.

These and other objects and advantages will appear from the description taken as a whole.

In accordance with this invention, as above indicated, there has been constructed a 'segmental pressure roll adapted for use in a grinding and polishing machine which comprises a body consisting of a plurality of segments disposed peripherally thereof, the peripheral surface of said segments being as to maintain the abrasive grains in contact with the work, yet sufilciently yieldable to permit localized areas of said hardened peripheral surface to recede towards the axis of the roll under grinding pressure. The segments are prepared, as by treating a suitable material with an impregnating agent, so as to render the peripheral surface hard without destroying the yieldability of the segment. The pressure roll is especially suitable for use in a grinding or abrading machine adapted to employ abrasive belts; also a grinding and polishing wheel or device is readily provided by placing an abrasive sleeve around the pressure roll. When the pressure roll is placed in motion, centrifugal force will press the peripheral surface of the roll firmly against the abrasive sleeve.

The invention may be illustrated by the attached drawing, in which:

Figure 1 shows a side elevational view of the pressure roll mounted in a grinding and abrading machine.

Figure 2 shows a view of the pressure roll with driving motor, and abrasive belt, taken on line 2-2 of Figure 1.

Figure 3 shows a side view partly in section (on an enlarged scale as compared with Figures 1 and 2) of the pressure roll around which an abrasive sleeve has been mounted, and illustrates the segments making up the outer portion of the roll.

Figure 4 shows a front view of the pressure roll, partly in section, and further illustrates the aforesaid segments.

Figure 5 shows a front view of a modified form of the pressure roll.

Figure 6 is an enlarged radial section view of a portion of the pressure roll.

Figure '7 is an end view of a single segment.

Figure 8 is an enlarged view showing details of construction of a portion of a segment.

Figure 9 is an enlarged side elevation of a modified form of a ply forming a part of a segment of the pressure roll.

Y Figure 10 is an enlarged end'view of the modifled form of segment ply of Fig. 9.

Figure 11 is an enlarged side elevation of a segment comprising several plies, as shown in Figs. 9 and 10; stitched together.

Figure 12 is an enlarged end view of the segment shown in Fig. 11.

In carrying out this invention Figures 1 and 2 show a method in which the segmental pressure roll may be employed. A motor drives a pressure roll 2|, around which an abrasive belt 22 passes, thebelt 22 also passing arounda pulley 23. The pressure roll 2| is provided with a body 24 consisting of a plurality of segments 25. The segments 25 are constructed and/or treated as hereinafter more fully described, so that the peripheral surface thereof will be of sufiicient hardness to permit of sufficient pressure against the abrasive-carrying belt as to firmly maintain the abrasive grains of the belt in contact with the work, and at the same time readily yieldable (except as affected by centrifugal force) to permit localized areas of the hardened peripheral surface to recede toward the axis of the roll under grinding pressure, so that the roll can conform to uneven or irregular areas on the surface being ground.

In Figure 3 another method in which the pressure roll may be employed is illustrated Thereof suflicient hardness so 4 in, an abrasive sleeve 28 is shown positioned around the pressure roll 2|.

In Figures 4 and 5 two types of peripheral surface are shown. In Figure 4 the unyieldable end of each of the segments adjacent to the periphe'ral surface has been cut so as to provide a plurality of fingers 21 forming the peripheral surface. In Figure 5 the unyieldable ends of the segments have been so constructed so as to provide one continuous surface 38 across the roll for each segment. The method of attaching the segments to the hub is also shown. A segment 25 is positioned in the roll. The end of the segment adjacent the axis of theroil is shaped by means of lathing, cutting, milling, stamping, etc., so that it'contalns two grooves or slots 28. Into these slots are placed side plates 29 which securely hold the segments 25. These side plates 29 are joined together and afllxed to the hub, as by means of rivets 30 (or, when joined together. they may constitute the hub).

Figure 6 is an enlarged view showing the manner in which a radially disposed segment is held to the hub. A segment 25, with a plurality of hard fingers 21, an impregnated base 3! and an unimpregnated, readily yieldable intermediate portion 32 is firmly amxed to side plates 29 by means of grooves or slots 28 and the side plates 29 are fixed to the hub or Joined together by means of rivets 30.

Figure 7 shows 'a side view of a single segment 25, showing the impregnated peripheral end 21. the impregnated base 3| and the untreated intermediate portion 32. Strips of material 33 have been inserted between the plies in the impregnated peripheral end 21, thus making the outer end 21 thicker than the inner end or base 3| of said segment. In some cases, as where the contact roll is to be used with abrasive belts to effect a polishing operation, e. g. where the abrasive belt is coated with abrasive particles of small grit size, it is desirable to have the outer ends 21 unimpregnated or substantially so, the outer portions still being dense and firm (because of its 3 construction) as compared with the readily yieldable intermediate portion 32.

Figure 8 shows the details of construction of a part of a single segment. Therein a strip of material 33 is shown amxed, e. g. adhesively,'at the peripheral end to a single ply 34 of the se ment.

The diameter of the wheels may be varied over a wide range, as well as may the size and number of the segments. The number of sheets or plies in each segment may be from 7 to 14, more or less, depending upon the weight of the cloth or other sheets, the degree of hardness desired in the surface characteristics of the finished contact wheel or roll, etc. The following table has been prepared as illustrative of the relationship of the length of the segment to the diameter of the pres- .sure roll which are often employed. However,

these may be varied as desired.

The width of the segments are commonly the same as the desired width of the finished pressure roll or wheel where the latter is of a width such as 2, 4 or 6 inches, more or less. However wheels or rolls 20 inches Wide have been made and use for still wider ones are anticipated, and in such wide wheels it is often more convenient to employ segments making up only a fraction of the total width of the roll or wheel. Wheels or rolls about 4 inches wide are common.

While any suitable method known to the art may be used in construction of the segments, a preferred method involves selecting suitable material, e. g. fabrics such as cotton shirting, canvas, or the like. It has been found that cotton cloth or shirting material, often called end cloth," is suitable for use. Such cloth may be cut diagonally into strips, on the bias. or otherwise formed into strips, preferably on the bias. The desired number of strips to make up a segment are cut to desired size, e. g. 4" (where the pressure roll is to be 4" wide) by 3" (where the total depth of the segment is to be 3") then the strips are sewed together. e. g. by two parallel stitchings. one A" from what will be the outer or pe ripheral end of the segment when attached in the finished wheel and the other about 1 from the inner end. Little strips of cloth 4" long (to correspond with the width of the segment) and /2" to wide (1. e. such as strips 33, Fig. 8) are then placed between the piles or sheets at the said outer or peripheral end of the segment and are joined thereto, adhesively or otherwise, e. g. by an adhesive aqueous solution of sodium silicate, which acts as an impregnating agent as well as an adhesive and. after drying, provides the se ment with a hard periphery, extending in for a depth of about This segment can then be sawed or cut in from the periphery where desired to provide fingers, such as fingers 21, Figures 4 and 6 of the drawing. However, where it is not desired to have so hard 9. surface, for example, where (as above indicated) the contact roll may be desired for use with abrasive belts of small grit sizes, e. g. for a polishing operation, I may simply stitch the plies and alternate strips 33a firmly together at the outer end 21a, thus to provide an outer portion which is firm and relatively unyieldable as compared with the intermediate portion 32a but less hard than is commonly the case where sodium silicate or the like is used as an impregnating agent for the outer ends 21. This modification is shown in Figures 9-12. In Figures 9 and 10 the stitching 39 secures the strips 33a to the outer ends 3411 of the plies. In Figures 11 and 12 the stitching. 40 secures the outer' ends 21a of the plies together to form a peripheral wheel segment which is less hard than the outer portions 2'! shown in Figures 6-8.

While the plies at the outer end of the segment are being impregnated and adhered together (where impregnation is used, as is common where the wheels are to be used with abrasive belts or sleeves to effect a grinding operation) the plies at the inner end (bounded by the inner stitching) are commonly also impregnated and adhered together, e. g. with an aqueous solution of sodium silicate, commonly without the insertion of any narrow strips between plies. Thus, following drying, with or without pressure, as needed, a segment is provided which is hard adjacent its outer or peripheral end and also adjacent its inner end, and is soft, yieldable and unimpregnated in the portion intermediate the hardened outer and inner portions. Also, the plies are free, i. e. not adhesively joined together,

in the said intermediate portion. The resulting segment is thicker adjacent the outer or peripheral end than adjacent the inner end thereof.

A suitable technique of joining these finished segmentsto the hub of a pressure roll or contact roll, so that they are radially disposed and constitute the periphery thereof, is quite well known in the art. Briefly a suitable procedure is as follows: i

A suitable number of the segments are arranged around the inside of a ring or hoop (much'like a steel barrel hoop), the hoop being a little larger than the diameter desired in the finished pressure roll. Short pieces of strap metal may be inserted at intervals between the segments if needed to provide the desired support during the next subsequent operation. The workman then transfers this ring or annulus of segments from the metal hoop to the inside of a tapered cylinder, where they are held in their circular or annular arrangement by pressure against each other and the inward pressure provided by the walls of the tapered cylinder. A metal ring is then placed on top of said segments, the same being of a diameter less than that of the tapered cylinder at that point and being greater than the smaller diameter of the annulus of segments. Pressure is then exerted downwardly on said ring to force the segments downwardly in the tapered cylinden After they have proceeded downwardly through the tapered cylinder for some distance, it may be necessary to employ a ring of slightly smaller diameter. Pressure downwardly on the annulus of segments is then continued and the same are forced from the bottom of the tapered cylinder into a ring (or metal hoop) of the desired size, in accordance with the.

desired siZe of the finished pressure roll. In forcing the segments through the aforesaid tapered cylinder rather substantial pressures are commonly required, which may, for example, range from about 10 tons for the smaller rolls to about 60 tons for the larger rolls. This ring or hoop, with the compressed segments held within it, is then secured to the face or support of a lathe, on which it can be rotated. Circular grooves or slots, such as the groove or slot 28, illustrated in Figure 6 of the drawing, are then cut in the annulus of segments. It will be evident that such slot is thereby provided in the inner hardened end of each segment. After the inner portion of such annulus of segments is thus grooved and/or shaped in accordance with the core or hub to which said annulus of segments is to be joined, said annulus of segments with the aforesaid iron ring or hoop still in place) is removed from the lathe and the hub members, or core members, are placed in position and attached to the said annulus of segments, for example, by drilling holes through the inner hardened ends of said segments, parallel to the width thereof, and joining the elements of the hub or core together by any suitable means, for example by rivets to provide a permanent article. The roll or wheel may now be placed in a separate press and pushed out of the aforesaid metal ring (which may be referred to as a retaining or peripheral ring). The compress roll or wheel is then in finished form,

except where there is substantial unevenness in the peripheral surface of the wheel due to the technique of making. In this case the periphery of the wheel or roll may be smoothed up, as by the use of a lathe, by rotating the same against the surface of a rapidly moving abrasive belt, or by other suitable means.

It will be evident that the making procedure is the same whether the finished compress roll is as illustrated in Figure 4 or as illustrated in Figure 5 or whether it constitutes some variation thereof, except that prior to forcing the segments through the tapered cylinder aforesaid the outer hardened ends of the individual. segments are sawed or out if a construction as illustrated in Figure 4 is desired.

While I have hereinabove illustrated specific materials and specific procedures by which the pressure roll of this invention may conveniently be made, such description is of course illustrative and not limitative as will be understood. While sodium silicate solution is a convenient and advantageous material for adhering and impregnating plies of each segment to form the hardened outer and inner portion, while leaving the central portion unimpregnated and flexible, as above described, I also contemplate the use of other materials, depending upon conditions, particular characteristics desired, etc. For example, various synthetic resins or solutions of synthetic resins, especially those of the heat advancing type, or having a suitable high melting point, may be used, including various phenol-aldehydes, urea-aldehydes, melamine aldehydes, alkyds and other resins.

While I have described the insertion of narrow strips between the plies at the outer or peripheral ends of the segments, to provide in creased thickness and denseness, it will be understood that thickness can be controlled within wide limits without employing this expedient, as by using increased amounts of impregnated material. Also, while the stiff outer ends of the segments are preferably made somewhat thicker than the inner ends thereof in the ordinary case, this is not an essential, even though it is an advantage in most cases.

While the inner ends of the segments are commonly made stiff, so as to be adaptable for grooving and attaching to hub members as above described, it will be understood that where the segments can conveniently be firmly attached to the hub or core without being stiff or impregnated, this can be dispensed with.

While the drawing illustrates a single circular slot 28 extending in from each side of the annulus of segments, where relatively wide pressure rolls are used and/or very high speeds of rotation are contemplated, the inner end of the annulus of segments may be arranged to provide one or more additional circular slots 28 farther in from the side of the wheel and closer to the inner ends of the segments. These can be arranged in a generally stair-step fashion, as will be easily visualized. This construction is sometimes necessary with rolls having a width of about 8 inches or more, or even on rolls of a lesser width where the strength and rigidity of the inner stiffened portions of the segment are low and/or where very high speeds of rotation of the pressure roller are contemplated.

/ scope of the appended claims are contemplated.

What I claim is:

1. A pressure roll adapted for supporting an abrasive belt and pressing it in contact with a work piece comprising a central hub or core and an annulus of radially disposed segments surrounding and mounted to said hub, the outer ends of said segments forming the circular periphery of said roll, said radially disposed segments each comprising continuous radially disposed strips of cloth, a substantial portion of each of said segments at the outer peripheral end thereof being impregnated to render it hard and to provide a hard, non-abrasive surface for said pressure roll and an inner portion of each said segment being flexible and readily yieldable.

' 2. A rotatable pressure roll adapted for driving an abrasive belt and holding the same in contact with an object to be ground or abraded comprising a central core and radially disposed segments surrounding and extending out from said core, each of said segments being firmly aflixed to and anchored by said core but otherwise bein free and unconnected with other segments and unconnected with other elements throughout its radial dimension, each said segment being readily flexible throughout at least about 40 percent of its radial dimension beyond the point where it is afiixed to said core but a substantial outer portion thereof being hardened by impregnation, each of said radially disposed segments having radially disposed continuous pieces of low and limited stretchability extending throughout the radial depth thereof, thereby providing a pressure roll with a hard, non-abrasive surface to efiic-iently back up an abrasive belt and yet one where any area thereof will readily yield and depress during use to conform to irregularities in the work piece, thus avoiding chattering of the work piece, and said roll being free of tendency to blow up or expand beyond a predetermined, desired circumferential size.

3. A rotatable pressure roll adapted for driving an abrasive belt and pressing it in contact with a work piece comprising a central core and radially disposed separate segments anchored and aiiixed to said core and extending outwardly therefrom, the outer ends of said'segments forming the circular periphery of said roll, the outer portion of each of said segments being hard, non-abrasive and uncompressible and the inner portion of said segment, between said hard outer portion and the point of fixation to said core, having a low and limited stretchability and having a good tensile strength and substantially no compression strength.

4. A grinding and abrading machine comprising an abrasive belt, a pressure roll for holdin said belt against a work piece during movement of the belt, and means for driving said belt, said pressure roll being as defined in claim 3.

5. A pressure roll for effecting contact of an abrasive belt-with Work to be ground or polished including a, plurality of radially disposed segments arranged to provide a peripheral annulus. each of said segments comprising a plurality of sheets of woven fibrous material, the outer end portion of each of said segments having said sheets joined together for a substantial portion of its length and being treated with a sodium silicate solution to render the said portion hard, while the central portion of said segment has said sheets unjoined and readily yieldable.

6. A grinding and polishing machine comprising an abrasive belt, means for moving said belt plurality of radial segments disposed peripherally thereof, each of said segments comprising material, a portion of which, along a substantial length of the segment at its outer end, has been treated to render it hard but non-abrasive, while the an abrasive belt on its periphery and to press the belt against an object being abraded, comprising a hub portion and an annulus of radially disposed segments surrounding and mounted to the hub portion, the outer end surfaces of the segments forming the rolls periphery, each segment comprising a tail portion by which the segment is fastened to the hub portion, a hard rigid, nonabrasive head portion which extends along a substantial portion of the segments radial length and whose outer end surface is a unit oi the rolls periphery and a flexible intermediate shank portion by which the head is suspended from the comprising material, a portion of which, along a 8. An abrading device comprising an abrasive sleeve superimposed around the peripheral surface of apressure roll and frictionally held thereon during use, said roll comprising a plurality of substantially radial segments disposed peripherally thereof, each of said'segments comprising material, a portion of which, along a substantial length of the segment at its outer end, has been constructed to render it relatively dense and hard, while the remaining portion is readily yieldable.

9. A pressure roll adapted for supporting an abrasive belt and pressing it in contact with a workpiece comprising a central hub or core and an annulus of radially disposed segments surrounding and mounted to said hub, the outer ends of said segments forming the circular periphery tail, the shank being of a length that will limit the centrifugally induced outward movement of the head during rotation to the distance that will give the composite roll its desired diameter, and the head of each, segment being movable in relation to the heads 01 the adjacent segments.

12. The presser roll of claim 11 in which the flexible shank portion of each segment occupies at least about 40% of the length of the segment that extends beyond the point'where the segment is afllxed to the hub portion and the head portion is of about the same length as the shank.

13. The presser roll of claim 11 in which each segment is a laminated structure formed of longitudinally disposed layers of flexible cloth with the of said roll, said radially disposed segments each comprising radially disposed sheets or Plies of cloth with a plurality of narrow strips of cloth intervening between said plies and extending across the width of each said segment adjacent the said outer end thereof, said plies and said narrow strips being joined together firmly over substantially the entire area of the narrow strips so as to render the outer end of said segment dense and firm while a portion of said segment of less radial distance from the axis of said roll has less thickness of plies and is flexible and readily yieldable.

10. A segment adapted to be'disposed radially in a contact roll for abrasive belts, said segment comprising a plurality of sheets or plies extending continuously throughout the radial dimension thereof and having additional narrow sheeted strips inserted alternately between the aforesaid plies for a substantial portion of said radial dimension near the outer or peripheral end thereof, said plies and narrow strips being joined together and impregnated to provide a unitary hard. thick head portion adjacent said outer end of said segment, and an inner portion of said segment, i. e. along the said radial dimension thereof, having said plies unioined and being flexible and readily yieldable.

11. A rotatable presser roll adapted to support head portion of the segment impregnated with a hardened plastic material which binds the cloth layers together to form ahard rigid head.

14. The presser roll of claim 11 in which each segment is -a laminated structure formed of longitudinally disposed layers of flexible cloth with the head portion formed of alternate layers of the cloth and of a hardened plastic material which binds the cloth layers together to form a hard rigid head.

15.'An expansible wheel for application to an endless abrasive belt, comprisingan annular rim a mounting, a series of truncated rim forming sections mounted face to face in annular formation. means forslidably supporting said sections upon said mounting to permit their radial movement relative thereto, said sections when retracted being adapted to engage the endless belt and being movable radially outward thereagainst under the influence of centrifugal force against said belt when rotated at operative speed.

HENRY R. HERCHENRHJER.

REFERENCES CITED The following references are of record'in the file of this patent:

UNITED STATES PATENTS Hillix Apr. 1, 1941 

